easy to grow,difficult to grow strains?

what makes a strain more difficult to grow then another...and whats to be expected when growing different strains then you are used to...how do you manage growing different strains at once

The reason different strains are harder is most the time the grow is build around a single strain or two. Meaning if you got bubba kush and lemon haze you always grow but now you wanna grow some white widow. The widow will need you to treat her differant the the last two strains. Having said that the strains are different to grow not difficult. Difficult because novice to the strain.